The dashed line is a comparison of the calculated position of Mars
with the Ptolemy/Copernicus systems, as carried out by Origanus, and its true position, as
calculated by Kepler (coming soon). The errors were plenty large enough to be obvious: 4
degrees is 8 times the diameter of the moon!(from Owen Gingerich,
"Johannes Kepler and the Rudolphine Tables," Sky and Telescope, December, 1971,
page 328)

If the earth is moving around the sun, then the nearest stars should exhibit
parallax relative to stars. No one had been able to observe any stellar parallaxes. So the
model violated a basic observation.

The parallax is smaller if the nearest stars are far from the earth,
but there was no compelling reason to put them so far away that it could not be
observed.(from Journey Through Astronomy, http://csep10.phys.utk.edu/).